Under normal operating conditions, an electric brake system for an aircraft relies upon a continuous power supply (or supplies) that provide operating power for the processing components, electric brake actuators, and other elements of the electric brake system. The power supply (which may include an active power source that is driven by the aircraft engine or engines and/or a backup power supply such as a battery) need not be devoted to the electric brake system and, therefore, the supply voltages for the electric brake system may fluctuate within system tolerances in response to the current power demands of the aircraft. Under certain operating conditions the electric brake system may experience a very brief power interrupt during which a supply voltage to the electric brake system drops below a specified voltage.
Even though aircraft typically recover from power interrupts in a very short time period, the resumption of nominal operating power for the electric brake system may result in discontinuous control of the electric brake actuators. Such discontinuities may cause the aircraft to lurch or apply the brakes in an unusual manner that is noticeable to the passengers and crew. For example, a power interrupt experienced during autobraking may trick the electric brake system, cause the control architecture to interpret the power interrupt as a lack of deceleration, and cause the control architecture to attempt an increase in the clamping force of the electric brake actuators in a compensating manner. Upon resumption of nominal operating power, however, the current state of the electric brake actuators may result in an “overbraking” condition that results in more deceleration than expected by the passengers and crew. On the other hand, a power interrupt experienced during pedal braking may cause the electric brake system to save the pre-interrupt values of the electric brake actuator control signals. Upon resumption of nominal operating power, however, the saved pre-interrupt values may not accurately reflect the current brake pedal deflection entered by the pilot. The effect on the aircraft will vary depending upon the difference (in both sign and magnitude) between the saved pre-interrupt values of the electric brake actuator control signals and the current post-interrupt values.